Existing methods of x-ray generation include (1) bremsstrahlung x-rays from a tube, (2) inverse Compton scattering in either a small linear accelerator (LINAC) [W. S. Graves, J. Bessuille, P. Brown, S. Carbajo, V. Dolgashev, K.-H. Hong, E. Ihloff, B. Khaykovich, H. Lin, K. Murari, E. A. Nanni, G. Resta, S. Tantawi, L. E. Zapata, F. X. Kärtner, and D. E. Moncton, “Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz,” 17 Phys. Rev. ST Accel. Beams 120701 (2014)] or a small storage ring [M. Bech, O. Bunk, C. David, R. Ruth, J. Rifkin, R. Loewen, R. Feidenhans'l and F. Pfeiffer, “Hard X-ray phase-contrast imaging with the Compact Light Source based on inverse Compton X-rays,” 16 J. Synchrotron Rad. 43-47 (2009)], and (3) large scientific facilities such as synchrotrons and x-ray free electron lasers.
Bremsstrahlung x-rays from a tube have low brightness, are not monochromatic except at fixed wavelengths, and are not coherent. While bremsstrahlung is the source of medical x-rays and is widely used for scientific work, it is many orders of magnitude less intense than the other sources. Inverse Compton scattering has demonstrated good performance but does not rely on coherent x-ray generation via a modulated beam and so it is orders of magnitude less efficient than the proposed method. Synchrotron and x-ray free electron laser facilities have the highest demonstrated x-ray performance but may cost in the range of $100 million to $1 billion and may have a size on the order of kilometers.
Some of the present inventors previously conceived of apparatus and methods for generating coherent radiation using an array of discrete electron beamlets from a nanocathode array, as described in U.S. Pat. No. 8,787,529 B2 (W. Graves, F. Kaertner and D. Moncton, “Compact Coherent Current and Radiation Source,” issued 22 Jul. 2014), which is herein incorporated by reference in its entirety.